US Patent 7812295 Optical system and method for multi-range and dual-range imaging

An imaging system is presented for use in multi-range imaging of an object scene by incoherent light. The imaging system comprises aligned a phase mask section, a single focus lens section, and a pixel detector array (PDA). The phase mask section has a generally non-diffractive, narrowly bounded, phase variation corresponding to a profile of a through-object Modulated Transfer Function (MTF) of the imaging system, where the profile has, at an at least one non-zero spatial frequency, at least two regions of growth leading to the MTF higher than 10%.